U.S. Market fences are ALL long, extending all the way to the back of
the table saw’s table, some even locking back there as well as in
front. Euro fences tend to be short - just long enough to extend a
little past the back of the saw blade when the blade is at maximum
height. Some can be shortened for shallower cuts.
When you think about it, beyond the back of the exposed blade PLUS the
distance to the riving knife, which keeps the kerf open, there really
isn’t any need to keep the stock behind the blade against the fence. In
fact, if the piece being ripped Wish Bones (I.e. Opens up like a “Y” )
it can push against the fence behind the cut and try to move the whole
piece of stock being ripped AWAY from the fence and bind against the
blade. In an extreme case, it could push the riving knive out of
alignment with the blade enough to allow the stock to contact the
blade’s rear teeth - the ones that typcially initiate a “kickback”. OR
- it could try and push the end of the fence away from the blade - also
not a “good thing”.
Now let us examine The Short Fence vs The Long Fence from a leverage
perspective. And let’s begin with both fences locked down only at the
front of the table. If you apply one pound of force to the end of a one
foot lever you produce one foot pound of torque. Apply the same one
pound of force to the end of a two foot lever and you produce TWO foot
pounds of torque - twice that of the one foot lever. Now if you’re
tying to lift something, the longer the lever arm the better. BUT - if
you’re trying to keep the lever from moving, which is what you want to
do if the lever is your rip fence, LONGER ain’t better at all, SHORTER
IS BETTER. Kind of obvious when you think about it - right?
OK - so what if we can lock down BOTH the front AND rear of the fence?
Well if you look at it from a Moment Diagram perspective - forces
applied to lever arms, The Short Fence vs The Long Fence Locked Down At
Both Ends is about a push - basically they’d work the same.
BUT - what’s it take to lock down both the front and rear of the fence
AND keep it parallel to the blade its entire length? If the back locks
down before the front, or the front locks down before the back, you
could cause the fence to go out of parallel with the blade. If the
front of the fence is closer to the line of the blade you’ll bind the
stock against the outside of the saw blade. If the front is farther
from the line of the blade you’ll bind the stock against the inside of
the blade. Neither situation is desirable.
ALL the mechanisms to lock the front and rear of the fence down together
and parallel to the saw blade introduce one more critical set up
requirement - AND one more thing that needs to be checked periodically
and adjusted if necessary. Don’t know about you, but I’d rather spend
time cutting wood rather than checking and adjusting things BEFORE I can
I can only think of one reason for a longer fence - a place to attach
Hold Downs behind the cut - Board Buddies, magnetic Draw-Tite etc. - all
keep the stock down on the saw table and some also pull the stock into
the fence. You don’t want the stock behind the blade coming up off the
table - and perhaps into those spinning teeth rising up out of the table
top. It’s those rear teeth that raise all the hell. ANYTHING that can
cause the stock to come in contact with those rear teeth is “not
good”. The Rear Teeth ARE BAD!
So other than the fact that you're use to a long fence is there any
reason why you wouldn't even consider going with a short fence?